Bead-based analysis of a sample

ABSTRACT

Among other things, two or more different antibodies are caused to bind to one or more units of a chemical component in a sample. Each of the antibodies is attached to one or more beads (e.g., microbeads). The sample is situated on a surface of an image sensor. At the image sensor, light is received originating at a light source that is other than the beads. The received light includes light reflected by, refracted by, or transmitted through the beads. The image sensor captures one or more images of the sample including the beads. At least one of the images of the sample is processed to separately enumerate individual beads and complexes of two or more of the beads attached to the two or more antibodies that are bound to a unit of the chemical component. The results of the processing are used to identify a presence or a level of the chemical component in the sample.

BACKGROUND

This description relates to bead-based analysis of a sample.

To obtain all the useful information in a sample of whole blood of apatient for purposes of diagnosis, for example, requires not only acomplete blood count (CBC) of the various types of blood cells in theblood sample and their hemoglobin content but also a chemical analysisof other components in the acellular portion of blood (e.g., theplasma). Such other components can include molecules and ions of variouskinds.

Traditionally, both a CBC and a chemical analysis of blood are performedin a lab on large expensive machines using tubes of venous bloodobtained by phlebotomy. Hours or days may be required for the chemicalanalysis to be completed and the results returned.

SUMMARY

In general, in an aspect, two or more different antibodies are caused tobind to each unit of one or more units of a chemical component in asample. Each of the antibodies is attached to one or more beads (e.g.,microbeads). The sample is situated on a surface of an image sensor. Atthe image sensor, light is received originating at a light source thatis other than the beads. The received light includes light reflected by,refracted by, or transmitted through the beads. The image sensorcaptures one or more images of the sample including the beads. At leastone of the images of the sample is processed to separately enumerateindividual beads and complexes of two or more of the beads attached tothe two or more antibodies that are bound to each unit of the chemicalcomponent. The results of the processing are used to identify a presenceor a level of the chemical component in the sample.

Implementations may include one or a combination of two or more of thefollowing features. The two or more different antibodies bind atdifferent locations of a unit of the chemical component. In some cases,the beads attached to at least two of the different antibodies have thesame reflective, refractive, and transmissive characteristics. In somecases, the beads attached to at least two of the different antibodieshave different reflective, refractive, or transmissive characteristicsor combinations of them for the light originating at the light source.The different reflective, refractive, or transmissive characteristicsinclude colors of the beads. The different reflective, refractive, ortransmissive characteristics include sizes of the beads. The differentreflective, refractive, or transmissive characteristics include shapesof the beads. The different reflective, refractive, or transmissivecharacteristics include birefringence of the beads. The situating of thesample on the surface of the image sensor includes forming a monolayerof the sample on the surface. The processing includes determining theamount of the chemical component in the sample based on a comparison of(a) the determined relationship between the number of the individualbeads and the number of the complexes of beads and (b) knownrelationships between the number of the individual beads and the numberof the complexes of beads in other samples having known amounts of thecomponent. The sample includes whole blood of a human or animal. Atleast one of the images is processed to determine counts of one or moretypes of blood cells in the sample. At least one of the images isprocessed to determine a complete blood count of the sample. The methodis done at a point-of-care.

In general, in an aspect, an image sensor has an array of lightsensitive elements exposed at a surface of the image sensor. The surfaceis configured to receive a sample containing units of a chemicalcomponent. At least one of the units of the chemical component has twoor more different antibodies bound to it. Each of the differentantibodies is attached to a single type of bead having the samereflective, refractive, and transmissive characteristics. A light sourceit is configured to illuminate the sample. The light sensitive elementsare configured to receive light from the light source including lightreflected by, refracted by, or transmitted through the beads. Aprocessor is configured to (a) receive one or more images captured bythe image sensor of the sample including the direct indicator beadsbased on the received light, (b) process at least one of the images toidentify individual beads and complexes of two or more of the beadsattached to the two or more antibodies that are bound to the unit of thechemical component, and (c) use information representing the identifyingof the individual beads and complexes of two or more beads to determinea presence or an amount or both of the chemical component in the sample.

In general, in an aspect, two or more different antibodies are caused tobind to one or more units of a chemical component in a sample. One ormore of the antibodies is attached to one or more beads. At leastanother of the antibodies is attached at a location on a surface. Thesample is applied on a surface of an image sensor, at the image sensor.Light is received originating at a light source and reflected by,refracted by, or transmitted through the one or more beads attached tothe antibody. The image sensor captures one or more images of the sampleincluding the one or more beads. At least one of the images of thesample including the one or more beads is processed to identify thelocation at which the antibody is attached on the surface, and thelocation is used to determine a presence or a level of the chemicalcomponent in the sample.

Implementations may include one or a combination of two or more of thefollowing features. The surface to which the antibodies are attachedincludes a surface of the image sensor. The surface to which theantibodies are attached includes a surface facing the surface of theimage sensor.

In general, in an aspect, an array of light sensitive elements isexposed at a surface of an image sensor. The surface is configured toreceive a sample containing one or more units of a chemical component.At least one of the one or more units of the chemical component hasbound to it two or more different antibodies. At least one of theantibodies is coupled to one or more beads. At least another of theantibodies is attached at a location on a surface. A light source isconfigured to illuminate the sample. The light sensitive elements areconfigured to receive the light originating at the source and reflectedby, refracted by, or transmitted through the one or more beads. Aprocessor is configured to (a) receive one or more images captured bythe image sensor based on the received light, (b) process at least oneof the one or more images to identify the location at which thebead-coupled antibody is attached to the surface, and (c) use thelocation to determine a presence or a level of the chemical component inthe sample.

In general, in an aspect, visible identifying markers are associatedwith units of chemical components of a sample. One or more images of thesample including the visible identifying markers are captured when thesample is in contact with a surface of an image sensor at which an arrayof light sensitive elements are exposed. The presence or the level ofone or more of the types of chemical components is determined based onthe captured images.

In general, in an aspect, a sample includes units of types of chemicalcomponents of a sample and visible identifying markers associated withthe units. An array of light sensitive elements is exposed at a surfaceof an image sensor. The image sensor is configured to capture one ormore images of the sample including the visible identifying markers whenthe sample is situated at the surface. A processor is configured todetermine the presence or the level of one or more of the chemicalcomponents based on the captured images.

In general, in an aspect, both a complete blood count and a chemicalanalysis are performed of a sample of whole blood on the surface of animage sensor at which an array of light sensitive elements are exposed.The complete blood count and the chemical analysis are based on lightoriginating at a light source other than the sample and reflected from,refracted by, or transmitted by the sample to the surface of the imagesensor.

In general, in an aspect, an array of light sensitive elements isexposed at a surface of the image sensor. The surface is configured toreceive a sample of whole blood. A light source is configured toilluminate the sample. The light sensitive elements are configured toreceive light originating from the source and reflected by, refractedby, or transmitted through the sample. A processor is configured toperform both a complete blood count and a chemical analysis of thesample of whole blood based on light originating at the light source andreflected by, refracted by, or transmitted through the sample to thesurface of the image sensor.

These and other aspects, features, implementations, and advantages (1)can be expressed as methods, apparatus, systems, components, programproducts, business methods, means or steps for performing functions, andin other ways, and (2) will become apparent from the followingdescription and from the claims.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a sample.

FIG. 2 is a schematic view of chemical analysis of a sample.

FIG. 3 is a schematic view of chemical analysis of a sample.

FIG. 4 is a graph of a standard curve.

FIG. 5 is a schematic view of a sample.

DETAILED DESCRIPTION

Here we describe a sample analysis technology that in someimplementations can perform a chemical analysis of a sample of wholeblood alone or in combination with a CBC directly at a point of carewithin a few minutes at low cost using a small portable easy-to-use,relatively inexpensive sample analysis device. In some uses, because ofits small size and low cost, the sample analysis device can bereproduced in large numbers and distributed to many locations within oneor more healthcare, residential, industrial, or commercial locations. Insome applications, many units of the sample analysis device can bedistributed and used in the field including at locations where equipmentfor sample analysis (for example, blood chemistry or CBC) is otherwiseunavailable or prohibitively expensive.

We use the term “point-of-care” broadly to include, for example, anylocation in close physical proximity to a patient or other person towhom healthcare is being provided. In many cases, point-of-care refersto services provided in the physical presence of a patient, for example,in the same room or building or at the same place or within a shortdistance.

Although much of the discussion below refers to applications of thesample analysis technology to chemical analysis of whole blood drawnfrom a human or other animal, the sample analysis technology can also beapplied to a wide range of contexts in which a sample (which may, butneed not, be a biological sample) contains chemical components ofinterest (such as molecules or ions) and that may not involve countingand may or may not include particles, units, or other elements of one ormore kinds that are to be counted.

We use the term “sample” broadly to include, for example, any fluid orother mass or body of material that contains one or more analyzablechemical components and may or may not also contain one or morecountable units of one or more types. The countable units may in somecases be opaque, translucent, or otherwise non-transparent to incidentlight. The analyzable chemical components may in some instances betransparent, translucent, or otherwise non-opaque to incident light. Insome examples, the sample is whole blood containing countable bloodcells of different types and also containing analyzable chemicalcomponents such as molecules or ions, to name two.

We use the term “chemical components” broadly to include, for example,chemical compounds, ions, molecules, and other constituents of a samplethat may not be present in a form of discernible (e.g., visible)countable units.

We use the term “unit of a chemical component” broadly to include, forexample, a single unit of a chemical component such as a singlemolecule, ion, or other constituent. In typical samples, there are manyunits of a given type of chemical component, for example, many moleculesof a chemical compound.

We use the term “countable units” broadly to include, for example,elements present in a sample that are discrete, discernible, visible,identifiable, and subject to enumeration. Typically, countable units arenot transparent. In the case of whole blood, the countable units caninclude blood cells of different types.

We use the term “chemical analysis” broadly to include, for example,identification and quantification (e.g., determination of the level) ofchemical components of one or more types in the sample. In some cases,chemical analysis can include identifying the presence of one or moremolecules of one or more types and characterizing the amount, volume, orpercentage of each of the types of molecules in the sample or in aparticular volume of the sample.

As noted earlier, although the sample analysis technology has a broaderrange of applications, for convenience we sometimes discuss particularexamples in which the sample comprises whole blood or components ofwhole blood.

We use the term “whole blood” broadly to include, for example, blood inits original form drawn from a human or other animal. Whole bloodincludes countable units such as blood cells and blood plasma thatincludes chemical components. As described in the Wikipedia entry titled“Blood plasma” blood plasma is “a yellowish liquid component of bloodthat normally holds the blood cells in whole blood in suspension. Inother words, it is the liquid part of the blood that carries cells andproteins . . . . It is mostly water (up to 95% by volume), and containsdissolved proteins (6-8%) (e.g. serum albumins, globulins, andfibrinogen), glucose, clotting factors, electrolytes (Na⁺, Ca²⁺, Mg²⁺,HCO₃ ⁻, Cl⁻, etc.), hormones, carbon dioxide (plasma being the mainmedium for excretory product transportation) and oxygen.” Clottingfactors include molecules such as plasminogen and prothrombin thatparticipate in clot formation.

We use the term “blood cells” broadly to include, for example, red bloodcells (erythrocytes), white blood cells (leukocytes), rare blood celltypes, ambiguous blood cell types, and platelets (thrombocytes).

As shown in FIG. 1, typical automated techniques 10 for chemicalanalysis of blood use fluorescence-based sandwich immunoassay techniquesto identify and quantify acellular chemical components 12, for example,molecules of one or more chemical components in blood plasma 14. The“filling” of the “sandwich” in fluorescence-based sandwich immunoassayis, for example, molecules 16 of a given target chemical component inthe blood plasma. Each of the molecules is, in effect, sandwiched 18 asa result of adding two types 20, 22 of antibodies to the blood sample.The antibodies of one type 20 are known to bind specifically to onelocation 24 on the target molecules and serve as “capture antibodies” inthe sense that they provide a known “base” at which the target moleculesare held. The antibodies of the other type 22 serve as “detectionantibodies” and are also known to bind specifically to the targetmolecules, but to a different location 26 on the target molecules. Insome examples, the capture antibodies are fixed, say, to a surface 28and literally “capture” the target molecules and holds them at aparticular location on the surface. The detection antibodies aretypically marked by fluorescent molecules 30 attached to them.

Once the target molecules have been captured, that is, bound to thecapture antibodies, high intensity excitation light 32 illuminates thesample in one wavelength band causing much lower intensity light to beemitted 34 from the attached fluorescent molecules in a different,typically longer, fluorescence wavelength band. The emitted light issensed by a light detector 36 (after being passed through a filter 38 toblock the much higher intensity excitation light). The light detector ishighly sensitive to the presence and intensity level of the relativelylow intensity fluorescence wavelength band light and can thereforegenerate signals indicating the fluorescence intensity and in turn theamount of the target chemical component present in the sample.

The fluorescence sandwich technique can be used to identify and quantifydifferent target chemical components of blood simultaneously by usingdifferent appropriate pairs of capture antibodies and suitably labelled(by fluorescent molecules) detection antibodies. In some implementationsof such multiplexing, the different capture antibodies are attached atdifferent locations to a fixed surface as a way to differentiate thedifferent target molecules based on their locations at the fixedsurface. In some implementations, the target molecules remain dissolvedor suspended in the sample and the different capture antibodies aremarked using fluorescent beads (for example, Luminex® beads) thatproduce fluorescence light in different wavelength bands, or differentcombinations of the bands, as a way to differentiate the different typesof target molecules without regard to their locations in the sample.

As discussed later, in some implementations of the sample analysistechnology, chemical analysis is combined with a contact monolayernon-fluorescence imaging technique for performing a complete blood count(CBC). For several reasons, the standard fluorescence sandwich techniquejust described is not optimally compatible with the contact monolayernon-fluorescence CBC technique. One reason is that, in the contact CBCtechnique, the blood sample is typically in direct contact with alight-sensitive surface of an image sensor which precludes the inclusionof a filter element between the surface and the sample to block the highintensity excitation light. A second reason is that the contact CBCtechnique is not readily compatible with washing and other processingsteps (one of which involves removing non-transparent blood cells fromthe sample) generally required in fluorescence sandwich immunoassaytechniques. The washing and processing steps cannot be easily applied ifthe same whole blood sample used for the sample analysis technique is tobe used also for the contact CBC technique. [Yet, as will be discussedlater, because the contact CBC technique is based on the use of amonolayer of blood, portions of the monolayer are free of blood cellsand contain only light-passing blood plasma. Therefore, although theentire area of the image sensor may not be suitable for chemicalanalysis of the target molecules because of the presence of blood cells,some portions of the area of the image sensor are suitable for thesample analysis technique even with whole blood.] A third reason why thefluorescent sandwich technique is not optimally compatible with thecontact CBC technique described above is that the small size pixels ofthe high-resolution image sensor do not provide as adequate low-lightsensitivity to detect the low intensity emitted fluorescence light ascan a larger-area light detector.

The sample analysis technology that is described here can be usedindependently to perform chemical analysis of whole blood or can be usedto perform chemical analysis of whole blood in combination with or tosupplement (simultaneously or sequentially) a contact CBC technique thatuses the same sample and light from the same light source. As a result,both the contact CBC technique and the blood chemical analysis can beperformed quickly at essentially the same time on a tiny sample of wholeblood (for example, a sample of less than 50 microliters or less then 15microliters or less then 5 microliters) at the point-of-care using asmall inexpensive device. Although we often discuss examples in whichthe chemical analysis is performed on whole blood, the sample analysistechnology can be applied to raw whole blood or to whole blood that hasbeen processed to alter or adjust or remove or supplement chemicalcomponents or to whole blood from which some or all of the blood cellshave been removed, including blood plasma.

We use the term “contact CBC technique” broadly to include, for example,any technique in which blood cells of one or more types are identifiedand counted in a sample that is in contact with (e.g., within anear-field distance of) a surface of an image sensor. Additionalinformation about contact CBC techniques can be found in one or more ofUnited States patent publications 2016/0041200, 2014/0152801,2018/0284416, 2017/0293133, 2016/0187235, and U.S. Pat. Nos. 9,041,790,9,720,217, 10,114,203, 9,075,225, 9,518,920, 9,989,750, 9,910,254,9,952,417, 10,107,997, all of which are incorporated here by reference.

Referring to FIG. 2, in some implementations of the sample analysistechnology, a monolayer 100 of whole blood is situated between a surface102 of a high resolution image sensor 104 at which an array ofphotosensitive elements (e.g., pixels) 106 are exposed and acorresponding surface 108 of a lid 110, to form a monolayer having aknown volume defined by its length, width, and thickness 112 between thesurface 102 and the surface 108. Examples of structures and techniquesfor forming such a monolayer are described in one or more of UnitedStates patent publications 2016/0041200, 2014/0152801, 2018/0284416,2017/0293133, 2016/0187235, and in U.S. Pat. Nos. 9,041,790, 9,720,217,10,114,203, 9,075,225, 9,518,920, 9,989,750, 9,910,254, 9,952,417,10,107,997, all of which are incorporated here by reference.

We use the term “high-resolution” broadly to include, for example, animage sensor that has a pixel spacing in one or both of two dimensionsthat is smaller than 5 μm, or 3 μm, or 1 μm, or sub-micron, for example.

We use the term “monolayer” broadly to include, for example, a volume ofa sample that has a thickness no greater than the thickness of aparticular type of unit in the sample, such as blood cells, so thatacross the monolayer two units cannot be stacked in the dimensiondefined by the thickness. In the case of a whole blood sample, thethickness of the monolayer could be in the range of 1 micrometer to 100micrometers.

Light 120 from a light source 122 illuminates the monolayer 100.Portions 124 of the light may pass through the sample monolayer and bereceived by photosensitive elements 126 in the array 128 of the imagesensor. Portions 130 of the light may be reflected or refracted bycomponents 131 of the monolayer and the reflected or refracted light maybe received by photosensitive elements in the array. Portions 132 of thelight may be transmitted through components of the monolayer and thetransmitted light may be received by photosensitive elements in thearray; portions of the light may be absorbed by components of themonolayer. As discussed later, the components of the monolayer caninclude countable units, chemical components, beads, and other elements.

The light source can be configured or controlled or both to provideilluminating light in one or more selected wavelength bands andcombinations of them. A wide variety of types of light sources andcombinations of them can be used, for example, LEDs, LED panels, organicLEDs, fluorescent panels, incandescent lamps, ambient illumination,arrays of monochrome LEDs, arrays of narrowband sources such as red,green, and blue LEDs or lasers, a miniaturized color display such as aliquid crystal or organic LED (OLED) display or an RGB laser colorprojector.

Using the light that originates at the light source and passes through,is reflected or refracted by, or is transmitted through the monolayer,the image sensor captures one or more images of the monolayer includingcountable units of various types (for example, blood cells) and chemicalcomponents that are detectable (either in their native condition or as aresult of being marked as discussed later). One or more of the capturedimages are processed by one or more processors or other image processingcomponents 113 to produce information 133 about the whole blood sampleincluding, for example, a CBC or a chemical analysis or both of thecountable units and chemical components. Among other things, theresulting information can include a count of red blood cells and theirhemoglobin content.

The CBC information can be generated by identifying and counting in thecaptured images the number of countable units of each type in thesample. Additional information about CBC techniques and about imagingusing contact image sensors can be found, for example, in United Statespatent publications 2016/0041200, 2014/0152801, 2018/0284416,2017/0293133, 2016/0187235, and in U.S. Pat. Nos. 9,041,790, 9,720,217,10,114,203, 9,075,225, 9,518,920, 9,989,750, 9,910,254, 9,952,417,10,107,997, all of which are incorporated here by reference.

As shown in FIG. 3, a monolayer 140 of whole blood (such as the samemonolayer of whole blood used for the contact CBC technique) can be usedfor chemical analysis of various chemical components 142, 144 of thewhole blood. For this purpose, individual units of the different typesof chemical components of the whole blood monolayer sample can betreated as fillings of sandwiches 148 similar to the fluorescentsandwiches. However, in implementations of the sample analysistechnology described here, capture antibodies 150, 152 and detectionantibodies 154, 156 are attached to beads 158, 160, 162, 164 that neednot have fluorescent properties and are directly visible or otherwisedetectable using light that originates at the light source and passesthrough, is reflected or refracted by, or is transmitted through themonolayer or components of the monolayer. The resulting light isreceived by light-sensitive elements (e.g., pixel) 166 arrayed in theimage sensor 168. (Unlike fluorescence techniques, the light source isnot within the monolayer sample but is external to it.)

Using the received light (in some cases, the same received light usedfor the contact CBC technique), the image sensor captures one or moreimages of the monolayer sample. One or more processors 170 or otherimage processing devices process the one or more received images andapply a variety of techniques to identify the presence of and determinethe level (e.g., quantity, amount, volume, percentage) of each of thechemical components in the sample.

The beads 158, 160, 160, 162 to which the antibodies 150, 152 and 154,156 are attached need not have fluorescent properties. The beads canhave characteristics that are detectable, visible, or otherwisediscernible based on light from the light source that is reflected from,refracted by, or passes through them. We sometimes refer to such beadsas “direct indicator beads”. The direct indicator beads can take theform of what are sometimes call microbeads in reference to their smallsize. Microbeads have sizes typically in the range of 0.5 to 500micrometers.

We use the term “direct indicator beads” (or sometimes simply “beads”)broadly to include, for example, any tag, marker, or other indicatordevice or indicator characteristic that can be attached to or associatedwith a chemical component of a sample and is identifiable at a sensorusing received light that was incident on and reflected or refracted byor transmitted through the indicator device or characteristic. In somecases, direct indicator beads can take the form of small grains,particles, beads, spherules, or other elements, and combinations ofthem, and can be of a variety of shapes, sizes, materials, and colors.

To determine the presence of units of chemical components in the sample,the processor analyzes the images to detect directly discerniblecharacteristics of beads and complexes of two or more beads that arerevealed by light originating from the light source and reflected from,refracted by, or transmitted through the beads to the surface of theimage sensor.

We use the term “directly discernible characteristics” of beads andcomplexes of beads broadly to include, for example, any quality,attribute, or other trait that can be detected, determined, or derivedfrom light that originated at a light source and was reflected from,refracted by, or transmitted through the beads. Directly discerniblecharacteristics could include color, size, texture, birefringence, orshape, or combinations of them, for example.

We use the term “complexes of beads” broadly to include, for example,two or more beads that can be associated with one another because theyare attached to a unit in a sample, such as a molecule or other chemicalcomponent. Typically, the two or more beads of a complex are detectablein constant close proximity (e.g., touching) one to another. In somecases, the two or more beads of a complex are detectable because theyhave two or more predetermined different directly discerniblecharacteristics. For example, two beads of a complex may have twospecific different colors that are discernible by processing the imagesfrom the image sensor.

The sample analysis technology that we describe here can be applied in avariety of different modes.

In some examples of one such mode, which we sometimes call thecomplexed-beads mode, the chemical components remain dissolved orsuspended in the sample. A capture antibody and a detection antibody,each coupled to a separate direct indicator bead, bind simultaneously tothe two different locations on a given target molecule or other unit ofa target chemical component to form a complex of two beads (i.e., adoublet). [Because each direct indicator bead has more than one of itsparticular (capture or detection) antibody bound to its surface, a beadmay participate in more than one such complex simultaneously, forming atriplet or higher-order bead complex.]

By processing one or more images captured by the image sensor, it ispossible to identify those beads present in doublets or higher-ordercomplexes, and thus associated with the chemical component. Bydetermining the proportion of complexed beads to the total number ofbeads (complexed and singleton, that is, uncomplexed) identified in thesample, it is possible to determine the level or amount or quantity orconcentration of the target units (e.g., molecules) of the chemicalcomponent in the sample.

It is true that identified singleton beads are not necessarily beadsunbound to the target molecule, because in some cases only the captureantibody or the detection antibody, but not both, may have bound to thetarget molecule.

However, under constant incubation conditions and provided that theconcentrations of bead-coupled capture antibodies and bead-coupleddetection antibodies in the sample are constant and their ratio isknown, it is possible empirically to establish a “standard curve” thatrepresents the relationship between the bead complex index (that is, theproportion of complexed beads to total beads identified by the device)and the concentration of the target molecule.

This has been done experimentally for prolactin to generate the standardcurve shown in FIG. 4. Using the standard curve, it is possible todetermine the otherwise unknown concentration of prolactin in a sampleby determining the bead complex index under identical incubationconditions.

In some implementations, the same beads can be used to mark both thecapture antibodies and the detection antibodies that will bind to givenunits of the chemical component. In some implementations, by usingcomplexes of beads having different directly discernible characteristicsfor capture antibodies and detection antibodies that are to be attachedto the units of different chemical components it is possible tomultiplex the process of detecting the presence and levels of thedifferent chemical components at the same time. Multiplexing can beachieved by using beads having different colors, sizes, shapes,textures, or other directly discernible characteristics.

As shown in FIG. 5, in some implementations, the capture antibodies 200are irreversibly bound to a fixed surface 202, for example differenttypes of capture antibodies are bound as spots 206 in knowncorresponding locations in an array 204 on the fixed surface. In suchimplementations the capture antibodies need not have direct indicatorbeads attached to them, but the detection antibodies would have directindicator beads attached to them. The fixed surface could be the surface108 of the lid 110 that faces the surface 102 of the image sensor 104and defines a gap occupied by the monolayer 100 of the sample. When themonolayer of the sample is in the gap and in contact with the printedspots in the array of capture antibodies, respective chemical componentsin the sample will bind to respective capture antibodies, based on thetype of the chemical components, in positions defined by the locationsof the printed spots in the array, and can at the same time bind todetection antibodies coupled to direct indicator beads. Images capturedusing incident light that passes through the monolayer and is reflected,refracted or transmitted by the direct indicator beads can then beprocessed to identify and determine the amounts of different types ofchemical components based on the imaged locations of the beads attachedto the detection antibodies. This technique of chemical analysis can beused separately or in combination with the contact CBC techniquediscussed earlier.

In some implementations, a combination of the location-based chemicalanalysis technique and the in-solution or in-suspension (that is,non-location-based, complexed-beads mode) chemical analysis techniquecould be used.

In order to use these chemical analysis techniques in combination withthe CBC technique in a point-of-care setting, steps must be taken toimpart the bead-coupled antibodies to the sample before it is loadedonto the image sensor surface. One approach would be to pass the sampleof blood taken from the patient through a tube where dried bead-coupledantibodies are solubilized by the blood and allowed to bind with thetarget molecules. Then the prepared sample can be placed on the sensorsurface. Another approach would be to deposit the bead-coupledantibodies onto the surface 108 of the lid 110 (in some cases inaddition to bead-free capture antibodies irreversibly bound at specificlocations of the lid) so that they are solubilized when the lidencounters the blood sample in forming the monolayer.

Other implementations are also within the scope of the following claims.

The invention claimed is:
 1. A method for identifying a presence or alevel of a chemical component in a sample, the method comprising bindingtwo or more antibodies to each unit of one or more units of a chemicalcomponent in a sample, each of the antibodies also being attached to oneor more beads, to form, for each unit of the chemical component, amulti-bead complex of two or more beads, two or more antibodies, and theunit of the chemical component, placing the sample on a surface of animage sensor, at the image sensor, receiving light originating at alight source, the received light including light reflected by, refractedby, or transmitted through the beads of the multi-bead complexes, at theimage sensor, capturing one or more images of the sample from thereceived light, enumerating, in at least one of the images of thesample, separate multi-bead complexes, the enumerating of the separatemulti-bead complexes comprising associating the two or more beads of themulti-bead complex based on close proximity to one to another, andidentifying, based on a result of the enumerating, a presence or a levelof the chemical component in the sample.
 2. The method of claim 1 inwhich the two or more antibodies bind at different locations of eachunit of the chemical component.
 3. The method of claim 1 in which thetwo or more beads of at least a portion of the multi-bead complexes havethe same reflective, refractive, and transmissive characteristics. 4.The method of claim 1 in which the two or more beads of at least aportion of the multi-bead complexes have different reflective,refractive, or transmissive characteristics or combinations of them forthe light originating at the light source.
 5. The method of claim 4 inwhich the different reflective, refractive, or transmissivecharacteristics comprise colors of the beads.
 6. The method of claim 4in which the different reflective, refractive, or transmissivecharacteristics comprise sizes of the beads.
 7. The method of claim 4 inwhich the different reflective, refractive, or transmissivecharacteristics comprise shapes of the beads.
 8. The method of claim 4in which the different reflective refractive or transmissivecharacteristics comprise birefringence of the beads.
 9. The method ofclaim 4 in which the different reflective, refractive, or transmissivecharacteristics comprise textures of the beads.
 10. The method of claim1 in which the placing of the sample on the surface of the image sensorcomprises forming a monolayer of the sample on the surface.
 11. Themethod of claim 1 in which the sample comprises whole blood of a humanor animal.
 12. The method of claim 11, comprising receiving, at theimage sensor, light originating at the light source and, in the sample,passing through only blood plasma.
 13. The method of claim 1 in whichthe sample comprises blood cells, the method comprising enumerating, inat least one of the images of the sample, blood cells of one or moretypes in the sample.
 14. The method of claim 13 comprising determining,based on a result of the enumerating of blood cells of one or more typesin the sample, a complete blood count of the sample.
 15. The method ofclaim 1 done at a point-of-care.
 16. The method of claim 1, comprisingcausing two or more antibodies to bind to one or more units of a secondchemical component in the sample, one or more of the antibodies bound toeach unit of the second chemical component being attached to one or morebeads, at least another of the antibodies bound to each unit of thesecond chemical component being attached at a respective known locationon a surface, wherein the respective known location of each of theantibodies on the surface corresponds to a type of each of theantibodies on the surface, identifying, in at least one of the images ofthe sample, the locations at which the antibodies are attached on thesurface having the antibodies attached, and based on at least one of theidentified locations being a known location corresponding to a type ofantibody, determining a presence or a level of the second chemicalcomponent in the sample.
 17. The method of claim 16 in which the surfaceto which the antibodies are attached comprises a surface of the imagesensor.
 18. The method of claim 16 in which the surface to which theantibodies are attached comprises a surface facing the surface of theimage sensor.
 19. The method of claim 1 comprising passing the samplethrough a tube before placing the sample on the surface of the imagesensor, the tube containing dried antibodies.
 20. The method of claim 1comprising, before placing the sample on the surface of the imagesensor, depositing dried antibodies onto the surface of the imagesensor.
 21. The method of claim 1 in which capturing the one or moreimages comprises capturing two or more images, and in which the receivedlight, for at least two of the two or more images, comprises light ofdifferent respective wavelengths.
 22. The method of claim 1 comprisingenumerating, in at least one of the images of the sample, separateindividual beads based on light reflected by, refracted by, ortransmitted by each of the separate individual beads and based on aproximity of each of the separate individual beads to other beads. 23.The method of claim 22 in which the identifying comprises determining anamount of the chemical component in the sample based on a comparison of(a) a determined relationship between a number of individual beads and anumber of multi-bead complexes and (b) known relationships between thenumber of the individual beads and the number of multi-bead complexes inother samples having known amounts of the chemical component.